The DNP-Rest is to PREVENT injuries & the low minutes is b/c players are most likely to pick up muscle injuries when they are fatigued. Look at the Bulls starters in the past 5 seasons, all of them have played high minutes & all of them have been chronically injured.
This only applies to those who expend energy on BOTH sides of the court, cats like James Harden can get away by taking a breather on defense.
There are also a couple of highly conditioned players who never get injured but that's like 5% of the league.